This invention relates to aerodynamic sliders and heads for disc storage drives, and particularly to manufacturing such sliders and heads.
Sliders and sliders containing magnetic heads are typically manufactured by thin-film techniques such that several thousands of sliders or slider/head combinations are formed from a single substrate or wafer. The wafer is sliced into row bars, and each row bar is mounted to a mount bar by an adhesive. The slider features, including rails and transducing heads, are defined on the row bar, which is lapped smooth to form an air bearing surface for each slider on the bar. The bars are then diced into individual sliders for subsequent assembly into disc drives.
Dicing is accomplished by cutting the bar at predetermined locations between sliders using a diamond cutting blade. The cutting locations are called xe2x80x9cdice lanesxe2x80x9dand are of a predetermined width, matching the width of the cutting blade. The dicing operation creates compressive stresses in the material at the edge surfaces of the slider. These compressive stresses create undesirable ridges in the topography of the air bearing surface of the slider. More particularly, the compressive stress propagates to form the undesirable ridges. Ridge formation at the edge of a slider due to dicing extends as much as 300 Angstroms (xc3x85) (0.03 microns) in height above the slider surface with a width as much as 50 microns from the edge surface of the diced cut. These ridges adversely affect the flying characteristics of the slider, and contribute to increased head crashes, particularly as the ridge height approaches the fly height of the slider.
There are several techniques to minimize formation of these ridges. One technique is to dice the bars into individual sliders using an ion milling process. Ion milling techniques generate virtually no stress in the slider material, thereby eliminating ridges altogether. However, ion milling is a slow process, compared to diamond blade dicing, and significantly increases the processing time for manufacture. Moreover, material milled by ion milling redeposits creating cleanliness issues. Consequently, ion milling is not an economically feasible option for dicing sliders in a production mode. A more conventional technique to minimize ridges is to position the rails having the air bearing surfaces far enough from the dicing lane so that compressive stress generated by the diamond saw dicing cannot propagate to the rail to form ridges thereon. However, this technique results in reduced air bearing surface area, thus degrading performance of the air bearing. Therefore, a need exists for an economically feasible technique for dicing bars into sliders using a diamond blade for cutting, without formation of ridges at the air bearing surface. The present invention provides a solution to this and other problems, and offers other advantages over the prior art.
The present invention is directed to minimizing the ridges formed during dicing operations.
In one form of the invention, a process is provided for dicing a bar to form a plurality of sliders each having an air bearing surface. A dice lane having a nominal surface is defined between adjacent slider portions on the bar. The dice lane has opposite edges defining respective edge surfaces of adjacent slider portions. The dice lane is cut away with a blade to form an edge surface of the slider. A barrier trench is formed in the nominal surface along each edge. The barrier trench has a predetermined depth and a width that extends a predetermined distance into the slider portion from the edge. The barrier trench inhibits formation of ridges on the air bearing surface.
In some embodiments, the barrier trench is formed in the bar at the edges of the dice lane before dicing the bar into sliders. In other embodiments, the barrier trench is formed in the sliders after the bar has been diced.
In one embodiment of the invention, the slider portions include rails defining the air bearing surface. The rails are positioned from the edge surfaces of the slider by a distance less than about 50 microns.
In another form of the invention a bar, formed of slider material, includes a plurality of slider features having an air bearing surface. A dice lane having a nominal surface is between adjacent slider features. Each dice lane has opposite edges along which the bar may be cut to remove the dice lane and separate the slider features into individual sliders. A barrier trench in the nominal surface extends along each edge of the dice lane. The barrier trench extends a predetermined distance into the slider features from the edge of the dice lane and to a predetermined depth from the nominal surface to prevent formation of ridges in the air bearing surface when the sliders are separated by a blade cutting away the dice lane.
The resulting slider is characterized by an absence of ridges in the air bearing surface.